Regeneration of acidic catalysts

ABSTRACT

A process for regenerating a used acidic catalyst which has been deactivated by conjunct polymers by removing the conjunct polymers so as to increase the activity of the catalyst is disclosed. Methods for removing the conjunct polymers include hydrogenation, addition of a basic reagent and alkylation. The methods are applicable to all acidic catalysts and are described with reference to certain ionic liquid catalysts.

FIELD OF THE INVENTION

The present invention relates to methods for the regeneration ofcatalysts and more specifically to the regeneration of acidic catalystsand to acidic ionic liquid catalysts.

BACKGROUND OF THE INVENTION

Ionic liquids are liquids that are composed entirely of ions. Theso-called “low temperature” Ionic liquids are generally organic saltswith melting points under 100 degrees C., often even lower than roomtemperature. Ionic liquids may be suitable for example for use as acatalyst and as a solvent in alkylation and polymerization reactions aswell as in dimerization, oligomerization acetylation, metatheses, andcopolymerization reactions.

One class of ionic liquids is fused salt compositions, which are moltenat low temperature and are useful as catalysts, solvents andelectrolytes. Such compositions are mixtures of components which areliquid at temperatures below the individual melting points of thecomponents.

Ionic liquids can be defined as liquids whose make-up is entirelycomprised of ions as a combination of cations and anions. The mostcommon ionic liquids are those prepared from organic-based cations andinorganic or organic anions. The most common organic cations areammonium cations, but phosphonium and sulphonium cations are alsofrequently used. Ionic liquids of pyridinium and imidazolium are perhapsthe most commonly used cations. Anions include, but not limited to, BF₄⁻, PF₆ ⁻, haloaluminates such as Al₂Cl₇ ⁻ and Al₂Br₇—, [(CF₃SO₂)₂N)]⁻,alkyl sulphates (RSO₃ ⁻), carboxylates (RCO₂ ⁻) and many other. The mostcatalytically interesting ionic liquids are those derived from ammoniumhalides and Lewis acids (such as AlCl₃, TiCl₄, SnCl₄, FeCl₃ . . . etc).Chloroaluminate ionic liquids are perhaps the most commonly used ionicliquid catalyst systems.

Examples of such low temperature ionic liquids or molten fused salts arethe chloroaluminate salts. Alkyl imidazolium or pyridinium salts, forexample, can be mixed with aluminum trichloride (AlCl₃) to form thefused chloroaluminate salts. The use of the fused salts of1-alkylpyridinium chloride and aluminum trichloride as electrolytes isdiscussed in U.S. Pat. No. 4,122,245. Other patents which discuss theuse of fused salts from aluminum trichloride and alkylimidazoliumhalides as electrolytes are U.S. Pat. Nos. 4,463,071 and 4,463,072.

U.S. Pat. No. 5,104,840 to describes ionic liquids which comprise atleast one alkylaluminum dihalide and at least one quaternary ammoniumhalide and/or at least one quaternary ammonium phosphonium halide; andtheir uses as solvents in catalytic reactions.

U.S. Pat. No. 6,096,680 describes liquid clathrate compositions usefulas reusable aluminum catalysts in Friedel-Crafts reactions. In oneembodiment, the liquid clathrate composition is formed from constituentscomprising (i) at least one aluminum trihalide, (ii) at least one saltselected from alkali metal halide, alkaline earth metal halide, alkalimetal pseudohalide, quaternary ammonium salt, quaternary phosphoniumsalt, or ternary sulfonium salt, or a mixture of any two or more of theforegoing, and (iii) at least one aromatic hydrocarbon compound.

Aluminum-containing catalysts are among the most common Lewis acidcatalysts employed in Friedel-Craft reactions. Friedel-Craft reactionsare reactions which fall within the broader category of electrophylicsubstitution reactions including alkylations.

Other examples of ionic liquids and their methods of preparation mayalso be found in U.S. Pat. Nos. 5,731,101; 6,797,853 and in U.S. PatentApplication Publications 2004/0077914 and 2004/0133056.

Hydrogenation in chloroaluminate ionic liquids in the presence of anelectropositive metal and HCl was reported by K. R. Seddon et al inChem. Commun., 1999, 1043-1044.

As a result of use, ionic liquid catalysts become deactivated, i.e. loseactivity, and may eventually need to be replaced. However, ionic liquidcatalysts are expensive and replacement adds significantly to operatingexpenses by in some cases requiring shut down of an industrial process.One of the heretofore unsolved problems impeding the commercial use ofchloroaluminate ionic liquid catalysts has been the inability toregenerate and recycle them. The present invention provides methods toregenerate acidic chloroaluminate ionic liquid catalysts overcoming thisobstacle and paving the way for the practical, commercial use of theseenvironmentally friendly catalysts.

SUMMARY OF THE INVENTION

Among other things the present invention provides a process forregenerating a used acidic catalyst which has been deactivated byconjunct polymers by removing the conjunct polymers so as to increasethe activity of the catalyst. Methods for removing the conjunct polymersinclude, but are not limited to, hydrogenation, addition of a basicreagent and alkylation. The methods are applicable to all acidiccatalysts and are described with reference to certain ionic liquidcatalysts.

BRIEF DESCRIPTION OF THE DRAWING

The FIGURE is a process diagram of an embodiment of a process inaccordance with the invention.

DETAILED DESCRIPTION

The present invention relates to a process for the regeneration of spentor deactivated acidic catalysts, including acidic ionic liquid-basedcatalysts i.e. those catalysts which have lost all or some of theircatalytic activity. The present process is being described andexemplified with reference certain specific ionic liquid catalysts andprocesses catalyzed thereby, but such description is not intended tolimit the scope of the invention. The methods described may be appliedto other catalysts and processes by those persons having ordinary skillbased on the teachings, descriptions and examples included herein.

The specific examples used herein refer to alkylation processes usingionic liquid systems, which are amine-based cationic species mixed withaluminum chloride. In such systems, to obtain the appropriate aciditysuitable for the alkylation chemistry, the ionic liquid catalyst isgenerally prepared to full acidity strength by mixing one molar part ofthe appropriate ammonium chloride with two molar parts of aluminumchloride. The catalyst exemplified for the alkylation process is a1-alkyl-pyridinium chloroaluminate, such as 1-butyl-pyridiniumheptachloroaluminate.

In general, a strongly acidic ionic liquid is necessary for paraffinalkylation, e.g. isoparaffin alkylation. In that case, aluminumchloride, which is a strong Lewis acid in a combination with a smallconcentration of a Broensted acid, is a preferred catalyst component inthe ionic liquid catalyst scheme.

While not being bound to this or any other theory of operation, thepresent invention is based in part on our discovery that one of themajor catalyst deactivation mechanisms is the formation of by-productsknown as conjunct polymers. The term conjunct polymer was first used byPines and Ipatieff to distinguish these polymeric molecules from theusual polymers. Unlike typical polymers, conjunct polymers arepolyunsaturated cyclic, polycyclic and acyclic molecules formed byconcurrent acid-catalyzed reactions including, among others,polymerization, alkylation, cyclization, and hydride transfer reactions.Conjunct polymers consist of unsaturated intricate network of moleculesthat may include one or a combination of 4-, 5-, 6- and 7-membered ringsin their skeletons. Some examples of the likely polymeric species werereported by Miron et al. (Journal of chemical and Engineering Data,1963) and Pines (Chem. Tech, 1982). These molecules contain double andconjugated double bonds in intricate structures containing a combinationof cyclic and acyclic skeletons.

The conjunct polymers deactivate the chloroaluminate ionic liquidcatalysts by weakening the acid strength of the catalyst through theformation of complexes of conjunct polymers and AlCl₃ possibly by meansof electron-donor/electron-acceptor interactions. The conjunct polymerswith their double bonds are the donors and the Lewis acid (AlCl₃) is theacceptor. Using their double bonds, the conjunct polymers coordinate tothe Lewis acid (AlCl₃) in the ionic liquid and rendering the coordinatedAlCl₃ for catalysis. Thus, the acidity of the catalyst becomes weakerand the overall catalytic activity becomes compromised and no longereffective for the intended purpose. Thus, the catalyst performance willbecome a function of the concentration of conjunct polymers in the ionicliquid phase. As more conjunct polymers accumulate in the ionic liquidphase the catalyst becomes less active. So, removal of all or a suitableportion of the conjunct polymers from the ionic liquid phase is asignificant aspect of the present process for ionic liquids catalystregeneration.

The term “conjunct polymer” as used herein also includes any otherspecies which might complex to AlCl₃ by pi bonding or sigma bonding orother means, which results in those species binding to the ionic liquid,so they are not removable by simple hydrocarbon extraction.

The formation of conjunct polymers has also been observed in otheracidic catalysts used in acid-catalyzed reactions, including HF, H₂SO₄and AlCl₃ alkylations. Conjunct polymers are also called “red oils” dueto their color and “acid-soluble oils” due to their high uptake in thecatalyst phase where saturated hydrocarbons and paraffinic products areusually immiscible. The methods of the present invention are applicableto those catalysts and processes.

It is believed that deactivation of the catalyst by the presence ofconjunct polymers is, in part at least, caused by coordination andcomplex formation between the Lewis acid AlCl₃ (electron pair acceptor)and the conjunct polymers (electron donors). In such complexes, theAlCl₃ is no longer available to act as a catalyst since it is tied-up inthe AlCl₃-conjunct polymers complexes. It also appears that the presence(or accumulation) of conjunct polymer molecules in the catalyst phase isnot by virtue of being miscible in the ionic liquid phase. Whileconjunct polymers may be somewhat miscible in the ionic liquids, theiraccumulation in the catalyst phase is more likely to being bound bystrong acid-base interactions (complexation) rather than being solublein the ionic liquid phase.

Conjunct polymers isolated from the catalyst phase by means ofhydrolysis are highly soluble in hydrocarbons. However, attempts toremove them from the catalyst phase prior to hydrolysis by simpleextraction methods with hydrocarbon solvents such as hexane, decane andtoluene were unsuccessful. Other more polar solvents such as CH₂Cl₂ orchloroform may dissolve a chloroaluminate ionic liquid and therefore arenot a selective solvent for dissolving and removing the conjunctpolymers. Conjunct polymers may be isolated by hydrolysis. However,these methods of isolating the conjunct polymers are destructive, andresult in an actual loss of a catalytic component (AlCl₃). Thehydrolysis methods hydrolyze the catalytic component (AlCl₃) andtransform it into inactive aluminum hydroxide and aluminum oxide. Thisindicates that the conjunct polymers are tightly held in the ionicliquid phase by fairly strong type of bonding system. Therefore, anysuccessful attempt to reactivate and regenerate the catalyst mustinvolve the removal of conjunct polymers to release aluminum trichloridefrom the AlCl₃-conjunct polymer complexes without destroying, consuming,or irreversibly tying up the AlCl₃.

In other words, one objective is to free the catalyst by replacing theconjunct polymers with other basic species that simply displace thepolymer without destroying the catalyst or by suppressing the ability ofconjunct polymers to form complexes with Lewis acids (aluminumchloride).

The deactivated catalyst can be revived in a nondestructive manner byfreeing up the AlCl₃ from conjunct polymer-AlCl₃ complex. In principle,this can be accomplished by saturation of the double bonds of theconjunct polymers to eliminate their ability to coordinate to the Lewisacid (AlCl₃). By hydrogenation, the double bonds of the conjunctpolymers will be saturated and no longer be able to be coordinated orcomplexed to AlCl₃. AlCl₃ no longer bound by conjunct polymers is thenreleased to take part in catalytic reactions.

Among other things the present invention provides a process for theremoval of the conjunct polymers from a used ionic liquid catalyst bysaturating the double bonds of the conjunct polymers by means ofhydrogenation thereby increasing the activity of the ionic liquidcatalyst.

Hydrogenation is a well-established process both in the chemical andpetroleum refining industries. Hydrogenation is conventionally carriedout in the presence of a catalyst which usually comprises a metalhydrogenation component on a porous support material, such as a naturalclay or a synthetic oxide. Nickel is often used as a hydrogenationcomponent, as are noble metals such as platinum, palladium, rhodium andiridium. Typical support materials include kieselguhr, alumina, silicaand silica-alumina. Depending upon the ease with which the feed may behydrogenated, the hydrogen pressures used may vary from quite low tovery high values, typically from about 100 to 2,500 psig.

The hydrogenation catalyst used in this invention may be any one ofmetallic or non-metallic catalysts which have hydrogenating ability. Thepreferred catalyst comprises at least one hydrogenation componentselected from Group VI-B and VIII, present as metals, oxides, orsulfides. Specific examples of the metallic catalysts are Fe, Co, Ni,Ru, Rh, Pd, Ir, Os, Pt, Cr, Mn, Ti, V, Zr, Mo, and W. Specific examplesof the non-metallic catalysts are Te and As. These metals or non-metalsmay be used singly or in combination.

Nobel metals such as palladium, platinum, or ruthenium, applied todiverse supports such as silicon dioxide, aluminum oxide, graphite, oractivated charcoal, are well suited for the hydrogenation of organic andinorganic compounds. The hydrogenation component may also be supportedon a refractory inorganic base, for example, alumina, silica, andcomposites of alumina-silica, alumina-boria, silica-alumina-magnesia,and silica-alumina-titania and materials obtained by adding zeolites andother complex oxides thereto. The refractory inorganic oxide is amaterial that has adequate mechanical strength and chemical stability atthe reaction temperature of the catalyst.

The catalyst of the present invention can be manufactured by supportingcatalytically active components on a catalyst carrier. The activecomponents may be deposited on the surface of the catalyst carrier afterthe carrier has been formed, or they may be incorporated into thecatalyst by being added to the carrier material during the formation ofthe catalyst carrier. Many such methods of preparation are known.

Hydrogenation may also be accomplished by using a metal or metal alloyhydrogenation catalyst. This hydrogenation catalyst may be any one ofthe various metallic catalysts which have hydrogenating ability. Thepreferred catalyst is selected from Group VI-B and VIII. Specificexamples of the metallic catalysts are Fe, Co, Ni, Ru, Rh, Pd, Ir, Os,Pt, Cr, Mn, Ti, V, Zr, Mo, and W. These metals may be used singly, incombination or as alloys. Catalysts such as Raney nickel and alloys suchas Ni/Al alloy may also be suitably employed.

The metals can be in the form of fine particles, granules, sponges,gauzes, etc. Each metal may be used in any number of forms: (1)macroscopic, which includes wires, foils, fine particles, sponges,gauzes, granules, etc.; and (2) microscopic, which includes powders,smokes, colloidal suspensions, and condensed metal films.

It is known that Raney-type-metal catalysts are prepared from alloyscontaining one or more catalytically 25 active metals (e.g., Ni, Co, Fe,Cu, Pd, etc.) and one or more catalytically inactive, easily dissolvablemetals (e.g., Al, Si, Mg, Zn). The catalytically active metal componentof the alloy is present in a so-called “dissolved” state, i.e. in afinely divided form. The inactive component is removed from the alloy byleaching the same with a solvent which does not attack the active metal.As solvents, generally aqueous alkaline solutions are used. During thisprocedure the active metal remains in the form of finely dividedcatalyst. The activity of the thus-obtained catalysts is higher thanthat of catalysts prepared, e.g., by reducing the appropriate metaloxides. This high activity explains the importance and the widespreaduse of such catalysts.

Hydrogenation may also be accomplished using a homogeneous hydrogenationcatalyst. Numerous examples of such catalysts are disclosed in U.S. Pat.No. 5,334,791, which is incorporated by reference herein.

Homogeneous hydrogenation catalysts for the production of hydrogenationreactants are well known in the art, with many systems being based onrhodium metal combined with phosphine ligands. Examples of suchcatalysts were first described in J. A. Osborn, F. H. Jardine, J. F.Young and G. Wilkinson, J. Chem. Soc. (A) (1966) 1711. Other examplesare soluble (homogenous) metal salts such as PdCl₂ and NiCl₂, andtransition metal complexes such as PdCl₂(triphenylphosphine)₂ andNiCl₂(triphenylphosphine)₂. Other organic metal complexes, e.g.,organometallic compounds of Ti, Ru, Rh, Zr, etc. are known to be usefulhomogeneous hydrogenation catalysts.

The Osborn et al. paper describes the hydrogenation of hydrogenatableproducts using a catalyst precursor of the formula[RhCl(triphenylphosphine)₃] and a pressure of hydrogen gas of oneatmosphere. U.S. Pat. No. 5,334,791 describes hydrogenation process fornon-aromatic unsaturated hydrocarbons using catalyst precursors based ona group VIIIB transition metal and a phosphine ligand.

Also of note is the use of chiral bis tertiary diphosphines inasymmetric hydrogenation with rhodium(I) catalyst precursors. There area number of patents related to synthesis and application of severalrhodium-chiral diphosphine catalyst precursors: See for example, U.S.Pat. Nos. 3,419,907; 3,849,490; 3,878,101; 4,166,824; 4,119,652;4,397,787; 4,440,936.

Other homogeneous hydrogenation catalysts and their method ofpreparation are described in F. Albert Cotton and Geoffrey Wilkinson,“Advanced Inorganic Chemistry”, Interscience Publishers, New York, 3rdEdition, 1972, pp 787 to 790.

Hydrogenation of use ionic liquid catalyst is shown by the followingexample. As noted previously, ionic liquid catalysts may becomedeactivated during use. For example, in an alkylate production unit,light (C₂-C₅) olefins and isoparaffin feeds are contacted in thepresence of a catalyst that promotes the alkylation reaction. In oneembodiment of a process in accordance with the present invention, thiscatalyst is a chloroaluminate ionic liquid. The reactor, which may be astirred tank or other type of contactor (e.g., riser reactor), producesa biphasic mixture of alkylate hydrocarbons, unreacted isoparaffins, andionic liquid catalyst containing some conjunct polymers. The densecatalyst/conjunct polymer phase may be separated from the hydrocarbonsby gravity decanter. This catalyst will be partially deactivated by theconjunct polymers binding to AlCl₃. The recovered catalyst can bereactivated in a reaction system hydrogenation with a supportedhydrogenation catalyst. The products of this step will be reactivatedcatalyst and hydrogenated conjunct polymers among others as describedherein. The reactivated catalyst and the hydrogenated conjunct polymerscan be separated, for example, by solvent washing, decantation, andfiltration.

In one embodiment of the present invention using hydrogenation, a usedionic liquid catalyst/conjunct polymer mixture is introducedcontinuously into a regeneration reactor, which contains a fixed bed ofa supported hydrogenation catalyst. Hydrogen gas and inert hydrocarbonsin which hydrogenated conjunct polymers are soluble are fed into thereactor at the desired rate. The solvent may be a normal hydrocarbonranging from C₅-C₁₅, preferably C₅-C₈. The residence time, temperatureand pressure of the reactor will be selected to allow adequatehydrogenation of the conjunct polymers. The reaction product iswithdrawn and sent to a separator. This mixture is then separated intothree streams, one comprising hydrogen and light hydrocarbons, a secondcomprising inert hydrocarbons and saturated conjunct polymer and a thirdcomprising regenerated ionic liquid catalyst. The denser and moreviscous regenerated catalyst phase settles to the bottom and can berecovered by means of a gravity decanter. The reactivated ionic liquidcatalyst is returned to the alkylation reactor. The solvent/conjunctpolymer mix is separated by distillation to recover the solvent.

A metal and a Broensted acid are used for hydrogenation in anotherembodiment of the present invention, which is described using aluminumand HCl. Aluminum metal reacts with HCl to give hydrogen gas and AlCl₃.By introducing aluminum metal and HCl into ionic liquid catalystsdeactivated by conjunct polymers, the hydrogen liberated can be used tosaturate the conjunct polymer double bonds. Concurrently, fresh aluminumchloride is produced, which is the acid component in the chloroaluminateionic liquid. This constitutes a two-function regeneration scheme forboth hydrogenating the conjunct polymers to release the complexed AlCl₃and producing fresh AlCl₃ which replenishes AlCl₃ that has been consumedor lost by other means during the reaction. The hydrogenated conjunctpolymers can be removed by solvent extraction or decantation and theregenerated ionic liquid catalyst recovered by filtration. Ourexperiments have shown that this scheme is feasible and that theregenerated catalyst demonstrated equal or better activity for thealkylation of ethylene with isopentane compared with freshly preparedcatalyst.

As seen from the prior description, an embodiment of a process accordingto the present invention utilizes hydrogenation to saturate the doublebonds of conjunct polymers using aluminum metal and hydrochloric acid.Using aluminum metal and HCl will produce the needed hydrogen gas forthe hydrogenation and will also produce fresh AlCl₃ that increases theacidity and the activity of the recycled catalyst by increasing theconcentration of AlCl₃ in the ionic liquid to its upper limits. In somecases, the regenerated catalyst will be more active than the freshlyprepared catalyst prior to being deactivated. The metal used in theregeneration process in accordance with the present invention is notlimited to aluminum. Other electropositive metals will react with HCl toproduce H₂ and the corresponding metal chloride can also be used. Thisincludes sodium, lithium, zinc, iron, copper, magnesium, titanium,gallium and many others. Aluminum metal will be the metal of choice whenchloroaluminate ionic liquids are used in the catalytic process to avoidcontamination of the regenerated ionic liquid with metal chlorides otherthan AlCl₃. While some metal chlorides may work as co-catalyst, othersmay inhibit the alkylation mechanism and promote unwanted reactionpathway. The process is not limited to using HCl as the source ofhydrogen. Other Broensted acids may also be used as a source of hydrogenincluding, but not limited to, HI, HBr, HF, H₂SO4, H₃PO₄. In the case ofchloroaluminate ionic liquids, hydro halides (HI, HCl, HBr, HF) will bethe acids of choice. Among the hydro halides hydrochloric acid ispreferred to avoid introduction of conjugate bases other than halidesand preferably other than chlorides.

As shown in the Examples, the conjunct polymers are removed byhydrogenation using aluminum and hydrogen chloride. Adding aluminum andhydrogen chloride to used ionic liquid catalyst and stirring theresulting mixture (in autoclave) at room temperature or at 50° C. at theautogenic pressure led to removal of >90% of the conjunct polymers ashydrogenated hydrocarbons. The hydrogenated conjunct polymers(immiscible in the ionic liquid phase) were removed by simple extractionmethods with other hydrocarbons (such as hexanes) or by means ofdecantation. The regenerated ionic liquid catalyst was removed from theremaining mixture (freshly made AlCl₃ and aluminum metal) by filtration.

The recovered regenerated ionic liquid catalyst was tested for activityby alkylating ethylene with isopentane and the regenerated catalystshowed better activity than both the deactivated catalyst and the freshcatalyst from which the deactivated catalyst was made. The selectivityof the regenerated catalyst was identical to the selectivity of thefreshly-made catalyst.

In an alkylate production unit, light (C₂-C₅) olefins and isoparaffinfeeds are contacted in the presence of a catalyst that promotes thealkylation reaction. In one embodiment of a process in accordance withthe present invention, this catalyst is a chloroaluminate ionic liquid.The reactor, which may be a stirred tank or other type of contactor(e.g., riser reactor), produces a biphasic mixture of alkylatehydrocarbons, unreacted isoparaffins, and ionic liquid catalystcontaining some conjunct polymers. The catalyst/conjunct polymer phasemay be separated from the hydrocarbons by means of a gravity decanter.This catalyst will be partially deactivated by the conjunct polymersbinding to AlCl₃. The recovered catalyst can be reactivated in areaction system employing aluminum metal and HCl. The products of thisstep will be reactivated catalyst and hydrogenated conjunct polymers.These can be separated by solvent washing, decantation, and filtration.

It is not necessary to regenerate the entire charge of catalyst. In someinstances only a portion or slipstream of the catalyst charge isregenerated. In those instances only as much ionic liquid catalyst isregenerated as is necessary to maintain a desired level of catalystactivity in the process in which the ionic liquid is used as thecatalyst.

In one embodiment of the present invention with reference to the FIGURE,the ionic liquid catalyst/conjunct polymer mixture is introducedcontinuously into a stirred tank reactor (CSTR), where aluminum metalpowder is added by way of a screw-type feeder. The aluminum is keptunder inert gas (nitrogen or other) to prevent oxidation. HCl gas is fedin at the desired rate to produce H₂ gas and AlCl₃. The residence timeof the reactor will be selected to allow adequate hydrogenation of theconjunct polymers. The reaction product is withdrawn and mixed with ahydrocarbon solvent (e.g., hexane) in which the hydrogenated conjunctpolymers are soluble. The solvent may be a normal hydrocarbon rangingfrom C₅-C₁₅; preferably C₅-C₈. This mixture is then separated in agravity decanter, from which the dense ionic liquid phase is withdrawn.Unreacted aluminum in the ionic liquid phase is removed by filtration.The reactivated ionic liquid catalyst is returned to the alkylationreactor. The solvent/conjunct polymer mix is separated by distillationto recover the solvent.

Hydrogenation conditions for all types of hydrogenation described hereinwill generally include temperatures of −20° C.-200° C., preferably50°-150° C., pressures of atmospheric-5000 psig, preferably 50-500 psig,and a contact time of 0.1 minute-24 hours, and preferably from ½-2 hoursin a normal hydrocarbon as a solvent.

In another embodiment of the present invention, an acidic catalyst isregenerated by adding a basic reagent which breaks up AlCl₃-conjunctpolymer complexes.

There are numerous reagents that can be used to break up theAlCl₃-conjunct polymer complexes including, e.g. amines. One importantconsideration is that any of these basic species would form, mostlikely, irreversible complexes with AlCl₃ similar to the AlCl₃-conjunctpolymer complexes. Moreover, there is no selective method to break upAlCl₃-conjunct polymer complexes. In other words, any reagent that maybe used to break up the AlCl₃-conjunct polymer complexes will also reactwith other aluminum species in the catalyst phase Therefore, to ensurethe complete break-up of the complexes by a reagent, sufficient reagentmust be added to react with all AlCl₃ molecules in the system, bothbound and unbound.

Since any reagent to be used in the removal process of conjunct polymersfrom the spent catalyst will form new complexes (e.g. AlCl₃-reagentcomplexes), thereby destroying active catalytic components, there willbe no gain from this procedure unless the reagent to be used is part ofthe catalyst system undergoing regeneration. Consequently, a processaccording to this invention, employs basic species that can displace theconjunct polymers and be part of the regeneration or recycling processof the catalyst. For example, in the butyl-pyridinium chloroaluminateionic liquid catalyst system, butylpyridinium chloride, where thechloride is the basic specie, would be used to break up theAlCl₃-conjunct polymer complexes in the spent catalyst.

Where, for example, the ionic liquid is formed by mixing either an aminehydrochloride or an alkyl ammonium halide with a Lewis acid, inaccordance with the present invention, a process whereby aluminumchloride is released from the AlCl₃-conjunct polymer complex isconducted by using either amines or ammonium chloride depending on theionic liquid that is being regenerated. More specifically, for1-butyl-pyridinium heptachloroaluminate, the conjunct polymers arereleased by adding butyl-pyridinium chloride to the deactivatedcatalyst. The chloride of the 1-butyl-pyridinium chloride interacts withthe non-complexed and complexed aluminum species in the spent catalystphase and thus freeing the conjunct polymers from the AlCl₃-conjunctpolymer complexes. The released conjunct polymers are then removed, forexample, by extraction with low boiling n-paraffins. The remaining solidresidues, presumably butylpyridinium tetrachloroaluminate, are convertedback to ionic liquid (butylpyridinium heptachloroaluminate) by addingmore AlCl₃ as set forth below.

Using this process, a stream of the catalyst is reactivated and theregenerated catalyst is recycled back into the reactor. By employing amethod according to the invention, the concentration of the conjunctpolymers can be minimized while the catalyst strength is maintained byreintroducing the regenerated catalyst into the reaction cycle.

The principle used for selecting a suitable reagent is not only limitedto using butylpyridinium in butylpyridinium chloroaluminate orbutylpyridinium chloroaluminate-like ionic liquids. It is applicable toionic liquids in general.

The reagent is one which corresponds to the basic parent species ofcation from which the ionic liquid to be regenerated was originallyproduced.

As a further example of this principle, consider ionic liquids that wereproduced from ammonium hydrohalides and aluminum chlorides. In thiscase, the basic reagent that is used to break up the AlCl₃-conjunctpolymer complex is the free amine corresponding to the ammoniumhydrohalide salt. Conjunct polymers are removed and ammoniumtetrachloroaluminate is produced. Addition AlCl₃/HCl is used tore-constitute the ionic liquid.

In summary, for aluminum chloride-based ionic liquid catalysts, adeactivated catalyst can be revived in a nondestructive manner byfreeing up the AlCl₃ from conjunct polymer-AlCl₃ complex. The processemploys the parent amine in the case of an ionic liquid catalyst derivedfrom ammonium hydrochlorides and aluminum halides, or employing alkylammonium halides when the ionic liquid catalyst is derived from alkylammonium halides and aluminum.

Addition of a basic reagent is shown by the following example. In analkylate production unit, light (C₂-C₅) olefins and isoparaffin feedsare contacted in the presence of a catalyst that promotes the alkylationreaction. In one embodiment of a process in accordance with the presentinvention, this catalyst is a chloroaluminate ionic liquid. The reactor,which may be a stirred tank or other type of contactor (e.g., riserreactor), produces a biphasic mixture of alkylate hydrocarbons,unreacted isoparaffins, and ionic liquid catalyst containing someconjunct polymers. The catalyst/conjunct polymer phase, which is denserthan other components, may be separated from the hydrocarbons by meansof a gravity decanter. This catalyst will be partially deactivated bythe conjunct polymers binding to AlCl₃. The recovered catalyst can bereactivated by first contacting the recovered catalyst withbutylpyridinium chloride in a first regeneration reactor to givebutylpyridinium tetrachloroaluminate and “free” conjunct polymer. Thefree conjunct polymer is removed. The remaining butylpyridiniumtetrachloroaluminate is then sent to a second regeneration reactor whereit is contacted with AlCl₃ to fully restore the activity of thecatalyst. The regenerated ionic liquid catalyst effluent of the secondreactor is then recycled to the alkylate production unit.

In one embodiment of the present invention using the addition of a basicreagent, a used ionic liquid catalyst/conjunct polymer mixture isintroduced continuously into a regeneration reactor along withbutylpyridinium chloride and inert hydrocarbons in which hydrogenatedconjunct polymers are soluble at the desired rate. The inerthydrocarbons may be a normal hydrocarbons ranging from C₅-C₁₅,preferably C₅-C₈ and their mixtures, although other hydrocarbons may beemployed. A conjunct polymer-hydrocarbon mixture is removed from thefirst regeneration reactor. The remaining butylpyridiniumtetrachloroaluminate is then sent to a second regeneration reactor whereit is contacted with AlCl₃ to fully restore the activity of thecatalyst. The regenerated ionic liquid catalyst is removed from thesecond reactor and can then be recycled.

Another method of regenerating a used acidic catalyst in accordance withthe present invention by reaction with an isoparaffin in the presence ofa Broensted acid, e.g. HCl. While not being bound to any theory, webelieve that reaction of isobutane with the double bonds in the conjunctpolymers leads to a partial or complete “capping” (alkylating) of theconjunct polymers double bonds disrupting their ability to complex to,e.g., aluminum trichloride. This is supported by our discovery thatolefin oligomers can be terminated and saturated by carrying out thechloroaluminate ionic liquid catalyzed oligomerization reaction in thepresence of isobutane.

In a process according to the present invention an isoparaffin feedstockis used to reactivate a used acidic ionic liquid catalyst. The simplestisoparaffin is isobutane. Isopentanes, isohexanes, isopentanes, andother higher isoparaffins may also be useable in the process of thepresent invention. Mixtures of light isoparaffins can also be used inthe present invention. Mixtures such as C₄-C₅ isoparaffins can be usedand may be advantageous because of reduced separation costs. Theisoparaffin feedstock may also contain diluents such as normalparaffins. This can be a cost savings by reducing the cost of separatingisoparaffins from close boiling paraffins. Normal paraffins will tend tobe unreactive diluents in the process of the present invention.

A preferred isoparaffin is one which has a tertiary carbon atom, i.e.one which is substituted by three alkyl or aryl groups and has oneremaining hydrogen and therefore is capable of participating in hydridetransfer reactions.

Broensted acids other than HCl may also be used in this embodimentincluding, but not limited to, HI, HBr, HF, H₂SO4, H₃PO₄. In the case ofchloroaluminate ionic liquids, hydrohalides (HI, HCl, HBr and HF) willbe the acids of choice. Among the hydrohalides, hydrochloric acid ispreferred. Other strong acids that are proton donors may also besuitably used.

In one example of this embodiment, the ionic liquid catalyst/conjunctpolymer mixture is introduced continuously into a reactor. HCl gas andisobutane are fed in to the reactor at the desired rate. The residencetime of the reactor will be selected to allow adequate alkylation of theconjunct polymers. The reaction product is withdrawn and mixed with ahydrocarbon solvent (e.g., hexane) in which the released conjunctpolymers are soluble. The solvent may be normal hydrocarbons rangingfrom C₅-C₁₅; preferably C₅-C₈. This mixture is then separated in agravity decanter, from which the denser ionic liquid phase is withdrawn.The reactivated ionic liquid catalyst is returned to the alkylationreactor. The solvent/conjunct polymer mix is separated by distillationto recover the solvent.

Typical alkylation reaction conditions generally may include atemperature of from −10° C. to +150° C., a pressure of from 0 psig to3500 psig, an isopentane to conjunct polymer molar ratio of from 0.5 to25 or more and a residence time of 0.5 min to 1 hour or longer

It is not necessary in any of the methods in accordance with theinvention to regenerate the entire charge of catalyst. In some instancesonly a portion or slipstream of the catalyst charge is regenerated. Inthose instances only as much ionic liquid catalyst is regenerated as isnecessary to maintain a desired level of catalyst activity in theprocess in which the ionic liquid is used as the catalyst.

The block diagram in the FIGURE is not meant to restrict the presentinvention any sort or type of reactor. Also, the FIGURE shows an inerthydrocarbon entering the reactor together with the deactivated ionicliquid. That is an optional implementation. The hydrocarbon could beleft out entirely or it could be added to the separator to allowextraction and separation simultaneously. Other modifications arepossible and are included in the scope of the present invention.

The following Examples are illustrative of the present invention, butare not intended to limit the invention in any way beyond what iscontained in the claims which follow.

EXAMPLES Example 1 Preparation of Fresh 1-ButylpyridiniumChloroaluminate Ionic Liquid Catalyst A (Fresh IL A)

1-butyl-pyridinium chloroaluminate is a room temperature ionic liquidprepared by mixing neat 1-butyl-pyridinium chloride (a solid) with neatsolid aluminum trichloride in an inert atmosphere. The syntheses ofbutylpyridinium chloride and the corresponding 1-butyl-pyridiniumchloroaluminate are described below. In a 2-L Teflon-lined autoclave,400 gm (5.05 mol.) anhydrous pyridine (99.9% pure purchased fromAldrich) were mixed with 650 gm (7 mol.) 1-chlorobutane (99.5% purepurchased from Aldrich). The autoclave was sealed and the neat mixtureallowed to stir at 125° C. under autogenic pressure over night. Aftercooling off the autoclave and venting it, the reaction mix was dilutedand dissolved in chloroform and transferred to a three liter roundbottom flask. Concentration of the reaction mixture at reduced pressureon a rotary evaporator (in a hot water bath) to remove excess chloride,un-reacted pyridine and the chloroform solvent gave a tan solid product.Purification of the product was done by dissolving the obtained solidsin hot acetone and precipitating the pure product through cooling andaddition of diethyl ether. Filtering and drying under vacuum and heat ona rotary evaporator gave 750 gm (88% yields) of the desired product asan off-white shiny solid. ¹H-NMR and ¹³C-NMR were consistent with thedesired 1-butyl-pyridinium chloride and no impurities were observed.

1-butylpyridinium chloroaluminate was prepared by slowly mixing dried1-butylpyridinium chloride and anhydrous aluminum chloride (AlCl₃)according to the following procedure. The 1-butylpyridinium chloride(prepared as described above) was dried under vacuum at 80° C. for 48hours to get rid of residual water (1-butylpyridinium chloride ishydroscopic and readily absorbs water from exposure to air). Fivehundred grams (2.91 mol.) of the dried 1-butylpyridinium chloride weretransferred to a 2-Liter beaker in a nitrogen atmosphere in a glove box.Then, 777.4 gm (5.83 mol.) of anhydrous powdered AlCl₃ (99.99% fromAldrich) were added in small portions (while stirring) to control thetemperature of the highly exothermic reaction. Once all the AlCl₃ wasadded, the resulting amber-looking liquid was left to gently stirovernight in the glove box. The liquid was then filtered to remove anyun-dissolved AlCl₃. The resulting acidic 1-butyl-pyridiniumchloroaluminate was used as the catalyst for the alkylation ofisopentane with ethylene.

Example 2 Preparation of “Deactivated” 1-Butylpyridinium ChloroaluminateIonic Liquid Catalyst (Deactivated Catalyst A)

“Deactivated” or “used” 1-butylpyridinium chloroaluminate ionic liquidcatalyst was prepared from “fresh” 1-butylpyridinium chloroaluminateionic liquid catalyst by carrying out the isobutane alkylation reactionin a continuous flow microunit under catalyst recycle with acceleratedfouling conditions.

The microunit consists of feed pumps for isobutane and butenes, astirred autoclave reactor, a back pressure regulator, a three phaseseparator, and a third pump to recycle the separated ionic liquidcatalyst back to the reactor. The reactor was operated at 80 to 100 psigpressure and with cooling to maintain a reaction temperature of ˜10° C.To start the reaction, isobutane, butenes, and HCl were pumped into theautoclave at the desired molar ratio (isobutane/butenes >1.0), throughthe back pressure regulator, and into the three phase separator. At thesame time, fresh chloroaluminate ionic liquid catalyst was pumped intothe reactor at a rate pre-calculated to give the desired catalyst/feedratio on a volumetric basis. As the reaction proceeded, ionic liquidseparated from the reactor effluent and collected in the bottom of thethree phase separator. When a sufficient level of catalyst built up inthe bottom of the separator, the flow of fresh ionic liquid was stoppedand catalyst recycle from the bottom of the separator was started. Inthis way, the initial catalyst charge was continually used and recycledin the process.

The following process conditions were used to generate DeactivatedCatalyst A (1-butylpyridinium chloroaluminate ionic liquid catalyst)from Fresh Catalyst A:

Process Variable Isobutane pump rate 4.6 g/min Butene pump rate 2.2g/min IL Catalyst pump rate 1.6 g/min HCl flow rate 3.0 SCCM pressure100 psig temperature 10 ° C.

The reaction was continued for 72 hours when it was judged that thecatalyst had become sufficiently deactivated.

Example 3 Determination of the Amounts of Conjunct Polymer and OlefinOligomers in Deactivated IL A

The wt % of conjunct polymers in the spent (deactivated) ionic liquidwas determined by hydrolysis of known weights of the spent catalyst. Theexample below is a typical procedure for measuring conjunct polymers ina given spent catalyst. In a glove box, 15 gm of a spent ionic liquidcatalyst in a flask were rinsed first with 30-50 ml of anhydrous hexaneto remove (from the spent catalyst) any residual hydrocarbon or olefinicoligomers. The hexane rinse was concentrated under reduced pressure togive only 0.02 gm of yellow oil (0.13%). Then, 50 ml of anhydrous hexanewas added to the rinsed catalyst followed by slow addition of 15 ml ofwater, and the mixture was stirred at 0° C. for 15-20 minutes. Theresulting mixture was diluted with additional 30 ml hexanes and stirredwell for additional 5-10 minutes. The mixture was allowed to settle downto two layers solution and some solid residue. The organic layer wasrecovered by decanting. The aqueous layer was further washed withadditional 50 ml hexanes. The hexanes layers were combined and driedover anhydrous MgSO₄, filtered and concentrated to give 2.5 gm (16.7 wt% of the spent catalyst) of viscous dark orange-reddish oil. It wasdetermined therefore that this particular spent catalyst contains 0.13%oligomers and 16.7% conjunct polymers. The hydrolysis can also beaccomplished using acidic (aqueous HCl) or basic (aqueous NaOH)solutions.

Example 4 Characterization of Recovered Conjunct Polymer fromDeactivated IL A

The recovered conjunct polymers according to the procedure described inExample 3 were characterized by elemental analysis and by infrared, NMR,GC-Mass and UV and spectroscopy methods. The recovered conjunct polymershave hydrogen/carbon ratio of 1.76 and chlorine content of 0.8%. ¹H-NMRand ¹³C-NMR showed the presence of olefinic protons and olefiniccarbons. Infra Red indicated the presence of olefinic regions and thepresence of cyclic systems and substituted double bonds. GCMS showed theconjunct polymers to have molecular weights ranging from 150-mid 600 s.The recovered conjunct polymers have boiling ranges of 350-1100° F. asindicated by high boiling simulated distillation analysis. UVspectroscopy showed a UV λ_(max) at 250 nm pointing highly conjugateddouble bonds systems.

Example 5 Hydrogenation of Deactivated IL A Using Al Metal and HCl andDetermination of the Amount of Residual Conjunct Polymers

Saturation of the double bonds of the conjunct polymers using aluminummetal and HCl was achieved according to the procedure shown below. To 40gm of spent ionic liquid containing 15.5 wt % (6.2 gm) of conjunctpolymers in 300 cc autoclave, 100 ml of anhydrous n-hexane and 9 gm ofaluminum were added. The autoclave was sealed (all done in glove box),and 10 gm of anhydrous HCl were introduced via an inlet. The reactionwas stirred at >1200 rpm and with intent of heating to 75° C. Thereaction was very exothermic and after few minutes the temperature roseto 81° C. and the pressure to 290 psi. Then, the pressure and thetemperature began to drop. At the end of the run (1.5 hrs) thetemperature was at 75° C. and the pressure was at 99 psi. The reactorwas cooled to room temperature and the organic phase was decanted off.The ionic liquid phase was rinsed twice with 50 ml anhydrous hexane. Thehexane layers were combined and concentrated under reduced pressure andheat to remove the solvent (hexane) giving 5.8 gm (93.5% of the weightof conjunct polymer originally present in the deactivated ionicliquid.). Hydrolysis of 10 gm of the treated ionic liquid gave 0.06 gmof conjunct polymers indicating a total of 4% remained in the ionicliquid phase. The hydrogenated products showed normal H/C ratios andNMR, IR and UV spectroscopy all indicated the disappearance of thedouble bonds.

Example 6 Determination of Activity of Deactivated IL A Using BatchAlkylation of isoPentane with Ethylene

The regenerated catalyst was highly active. The activity of theregenerated ionic liquid catalyst matched the activity of the freshlyprepared catalyst in the alkylation of ethylene with isopentane to makeC₇s. Table 1 compares the activity of the regenerated catalyst with thefreshly prepared and the spent catalysts in the alkylation of ethylenewith isopentane. The alkylation of isopentane with ethylene was doneaccording to the procedure describe below. A 300 cc autoclave wascharged with 20 gm of ionic liquid catalyst, 100 gm anhydrousisopentane, 10 gm ethylene and 0.3 gm anhydrous HCl. The reaction wasthen stirred ˜1200 rpm and heated to 50° C. at autogenic pressures. Thestarting pressure was usually 280-320 psi. The reaction was usuallycomplete when the pressure dropped down to single digits. In the case ofslow going reaction, the reaction was allowed to go on for 1 hr. At theend of the reaction, the reactor was vented out and a gas sample waschecked by GC for ethylene concentration. The liquid reaction mixturewas allowed to settle into 2 phases. The organic phase was decanted andanalyzed for product distribution by GC analysis. The following Table 1draws a comparison among the freshly made, the spent and the regeneratedcatalysts.

TABLE 1 Regenerated. Fresh Catalyst Spent Catalyst Catalyst ReactionTime 9 min. 60 min. 6 min. Starting 300 psi 286 psi 297 psi PressureEnding pressure 11 302 psi 7 iC5 72    98% 67 C7s 19 ~1.4% 192,3-DM-Pentane 8.23 0.9 9 2,4-DM-Pentane 10 0.6 10 2,3DM/2,4DM 0.82 1.50.9

Example 7 Removal of Conjunct Polymer from Deactivated Catalyst A by theAddition of Pyridine

Note that a process based on this example would require the addition ofHCl and AlCl₃ in the second regeneration reactor. In this case, thecation of the ionic liquid is pyridinium hydrochloride chloride, with H—instead of butyl-.

Deactivated Catalyst A (10.022 g) containing 24.6% conjunct polymers wasweighed into a bottle and treated with 2.24 g of pyridine. Afterstirring for 45 minutes at ambient temperature, the contents of thebottle were extracted three times with 6.8 g of hexane. The hexaneextracts were combined and evaporated under a stream of nitrogen. Thenet weight of residue was 1.84 grams or 18.4 wt %. The starting spentionic liquid contained 24.6% conjunct polymers.

Example 8 Removal of Conjunct Polymer from Deactivated Catalyst A by1-Butyl-Pyridinium Chloride

In a round bottom reaction flask equipped with stirring bar and dryingtube (CaCl₂ drying tube) 100 gm of anhydrous hexane were added to 20 gmof spent butylpyridinium chloroaluminate ionic liquid catalystcontaining 16 wt % (3.2 gm) conjunct polymers. Five grams ofbutylpyridinium chloride was added to the 20 gm of spent catalystalready in 100 ml anhydrous hexane. The reaction was stirred for 30 min.and the hexane layer was decanted off. The residue was rinsed with anadditional 50 ml hexane. The hexane layers were added and concentratedto give 1.2 gm of possible 3.2 gm of conjunct polymers. An additional 3gm of butylpyridinium chloride and 50 ml anhydrous hexane were added tothe ionic liquid residue from the treatment of the first 5 gm ofbutylpyridinium chloride and the mixture was stirred for ˜15-20 minutes.The reaction mixture turned into two phases. One phase consisted ofgranulated brown solids and the hexane layer containing the remainder ofthe conjunct polymers. The hexane layer was decanted off and theremaining solids were rinsed with additional 50 ml anhydrous hexane. Thehexane layers were combined and concentrated on a rotary evaporator togive additional 1.95 gm of conjunct polymers (in addition to the 1.2 gmrecovered from the first addition of butylpyridinium chloride). Thus, atotal of 3.15 gm or 98.4% of the conjunct polymers present in the spentcatalyst were removed. The above procedure was repeated with similarresults using other spent catalysts with varying conjunct polymerscontents.

The recovered conjunct polymers removed by the procedure described aboveexhibited all the physical and spectroscopic characteristics of conjunctpolymers isolated by hydrolysis methods.

The recovered solid were stripped off the solvent (not to dryness) on arotary evaporator at 14 torr and 60° C. To the obtained brown solids, inan Erlenmeyer flask in a glove box, 6.5 gm of AlCl₃ were slowly addedwhile stirring. After all the AlCl₃ was added, the resulting liquid wasallowed to stir for additional 30 minutes. The liquid was then filteredand used for alkylation of ethylene with isopentane as a test for theactivity of this partially regenerated ionic liquid catalyst.

Example 9 Determination of the Activity of the RegeneratedButylPyridinium Chloroaluminate Ionic Liquid Catalyst

The regenerated butylpyridinium chloroaluminate ionic liquid catalystdescribed in Example 8 was tested for activity by using it as thecatalyst in the alkylation of isopentane with ethylene and comparing itwith freshly-made catalyst. The alkylation of isopentane with ethylenewas done according to the following procedure. A 300 cc autoclave wascharged with 20 gm of ionic liquid catalyst, 100 gm anhydrousisopentane, 10 gm ethylene and 0.3 gm anhydrous HCl. The reaction wasthen stirred ˜1200 rpm and heated to 50° C. at autogenic pressures. Thestarting pressure was usually 280-320 psi. The reaction was usuallycomplete when the pressure dropped down to single digits. In the case ofslow going reaction, the reaction was allowed to go on for 1 hr. At theend of the reaction, the reactor was vented out and a gas sample waschecked by GC for ethylene concentration. The two phase reaction mixturewas allowed to settle into catalyst phase (lower phase) and thehydrocarbon phase (the upper phase). The hydrocarbon phase containingthe feeds and the alkylation products was decanted and analyzed forproduct distribution by GC analysis.

Table 2 below shows the ethylene/isopentane alkylation results of thisregenerated catalyst compared with the alkylation results of the freshand the spent catalyst.

TABLE 2 Fresh Catalyst Spent Catalyst Regen. Cat. Reaction Time 9 min.60 min. 14 min. Starting 300 psi 286 psi 280 psi Pressure Endingpressure 17 302 psi  4 psi iC5 72    98% 69.4% C7s 19 (72%) ~1.4% 20.1%2,3-DM-Pentane 8.23 (31.5%) 0.9 10.7% 2,4-DM-Pentane 10 (38%) 0.6 8.9%2,3DM/2,4DM 0.82 1.5 1.2 Alkylation of ethylene with isopentane atiC5/C2⁼ of 4 @ 50° C.

From the table above, the activity of the regenerated catalyst iscomparable to that of the fresh catalyst. The spent catalyst containingthe conjunct polymers is inactive.

Example 10 Removal of Conjunct Polymers from Deactivated Catalyst A byHydrogenation with Palladium on Carbon Catalyst

In a drybox, 3.0 grams of 10% palladium on carbon (Pd/C) catalyst wascharged to a 100 mL stirred autoclave. Next, ˜30 mL (31.33 g) ofDeactivated Catalyst A was added. The autoclave was taken out of thedrybox and charged with 900 psig hydrogen at ambient temperature. Thereactor was heated to 100° C. for 14.75 hours and then cooled. A portionof the recovered catalyst (22.48 g) was extracted three times with 7 gof dry hexane. The hexane extracts were combined and evaporated under astream of nitrogen to yield 0.408 g of clear, colorless oil. Thiscorresponds to a recovery of 9.9 wt % of the conjunct polymer originallypresent in the Deactivated Catalyst A.

An 11.26 g sample of hexane-extracted, hydrogenated Deactivated CatalystA was weighed into a bottle and hydrolyzed as described in Example 3.After combining the hexane extracts and evaporation under a stream ofnitrogen, 0.87 g of a non-volatile residue was recovered. Thiscorresponds to 7.73 wt % conjunct polymer remaining on the DeactivatedCatalyst A after hydrogenation with 10% Pd/C catalyst. This correspondsto removal of 37.2 wt % of the conjunct polymer originally present inDeactivated Catalyst A. The difference between 9.9% hydrogenatedconjunct polymer recovered and 37.2% conjunct polymer removed fromDeactivated Catalyst A is due to losses during hexane evaporation oflight components formed by hydrocracking.

Example 11 Removal of Conjunct Polymer from Deactivated Catalyst B byHydrogenation with Palladium on Carbon Catalyst

The procedure of Example 10 was repeated using Deactivated Catalyst B(31.33 g). The amount of 10% Pd/C catalyst was 0.10 g. Hexane, 30 mL,was also added to aid stirring. The initial pressure at ambienttemperature was 900 psig. After heating 18 hours at 100° C. and cooling,the pressure was 650 psig. After extraction of hexane and evaporation oflight components, 0.43 g of clear, colorless, oil was recovered. Thiscorresponds to a recovery (as hydrogenated conjunct polymer) of 5.92 wt% of the original conjunct polymer present in Deactivated Catalyst B.

A sample of 15.009 g of Deactivated Catalyst B after hydrogenation andhexane extraction was placed in a bottle and hydrolyzed as described inExample 3. After hexane extraction and evaporation of the volatiles fromthe combined hexane extracts, a residue of 1.56 g of conjunct polymerwas obtained. This corresponds to conjunct polymers content afterhydrogenation of 10.4 wt %. Alternatively, 61.6 wt % of the conjunctpolymer originally present in Deactivated Catalyst B was removed byhydrogenation.

Example 12 Removal of Conjunct Polymer from Deactivated Catalyst C byHydrogenation with Palladium on Alumina Catalyst

The procedure of Example 10 was repeated using Deactivated Catalyst C(21.278 g). The hydrogenation catalyst was 1.04 g of 1.0 wt % Pd onAl₂O₃. In this experiment, no hexane was added to aid stirring. Theinitial pressure at 100° C. was ˜1212 psig and after heating 4.5 hoursat 100° C., the pressure was ˜1090 psig. After extraction of hexane andevaporation of light components, no oil was recovered.

A sample of 17.33 g of Deactivated Catalyst C after hydrogenation andhexane extraction was placed in a bottle and hydrolyzed as described inExample 3. After hexane extraction and evaporation of the volatiles fromthe combined hexane extracts, a residue of 1.49 g of conjunct polymerwas obtained. This corresponds to conjunct polymer content afterhydrogenation of 8.60 wt %. Alternatively, 37.4 wt % of the conjunctpolymer originally present in Deactivated Catalyst C was removed byhydrogenation.

Example 13 Removal of Conjunct Polymer from Deactivated Catalyst C byHydrogenation with Supported Platinum on Alumina Catalyst

The procedure of Example 10 was repeated using Deactivated Catalyst C(20.78 g). The hydrogenation catalyst was 1.46 g of 0.5 wt % Pt onAl₂O₃. In this experiment, no hexane was added to aid stirring. Theinitial pressure at 100° C. was ˜1250 psig and after heating 4.5 hoursat 100° C., the pressure was ˜1190 psig. After extraction of hexane andevaporation of light components, no oil was recovered.

A sample of 17.55 g of Deactivated Catalyst C after hydrogenation andhexane extraction was placed in a bottle and hydrolyzed as described inExample 3. After hexane extraction and evaporation of the volatiles fromthe combined hexane extracts, a residue of 2.18 g of conjunct polymerwas obtained. This corresponds to a conjunct polymer content afterhydrogenation of 12.4 wt %. Alternatively, 9.7 wt % of the conjunctpolymer originally present in Deactivated Catalyst C was removed byhydrogenation.

Example 14 Removal of Conjunct Polymer from Deactivated Catalyst C byHydrogenation with Supported Ni Catalyst

The procedure of Example 10 was repeated using Deactivated Catalyst C(19.20 g). The hydrogenation catalyst was 1.02 g of Ni on synthetic micamontmorillonite. The hydrogenation catalyst had been previously reducedin flowing hydrogen at ambient pressure and at 450° C. In thisexperiment, no hexane was added to aid stirring. The initial pressure at100° C. was ˜1250 psig and after heating 4 hours at 100° C., thepressure was ˜1200 psig. After extraction of hexane and evaporation oflight components, no oil was recovered.

A sample of 15.76 g of Deactivated Catalyst C after hydrogenation andhexane extraction was placed in a bottle and hydrolyzed as described inExample 3. After hexane extraction and evaporation of the volatiles fromthe combined hexane extracts, a residue of 1.82 g of conjunct polymerwas obtained. This corresponds to conjunct polymer content afterhydrogenation of 11.6 wt %. Alternatively, 16.0 wt % of the conjunctpolymer originally present in Deactivated Catalyst C was removed byhydrogenation.

Example 15 Removal of Conjunct Polymer from Deactivated Catalyst A byHydrogenation over Ni—Al Alloy

As a way for regenerating deactivated chloroaluminate ionic liquids, 35gm of spent ionic liquids containing 22.3 wt % (7.8 gm) conjunctpolymers in a 300 cc autoclave, 2 gm of Ni—Al alloy and 70 ml ofanhydrous hexane were added. The autoclave was sealed and pressurizedwith hydrogen to 500 psi and heated to 100° C. while stirring at >1200rpm for ˜1.5 hrs. The starting pressure was 500 psig at roomtemperature. As the autoclave heated up, the pressure rose to 620 psig.As the reaction continued, pressure dropped to 560 psig and remained atthat pressure for the remainder of the reaction time. The reactor wascooled down and to the contents allowed to settle. The resultantreaction mixture contained the hexane layer (the top layer), the ionicliquid layer (the bottom layer) and the Ni—Al alloy settled to thebottom of the reactor. The hexane layer was decanted off and saved. Theionic liquid layer was rinsed 3×50 ml anhydrous hexane. The hexane fromthe reaction and all hexane rinses were combined and dried over MgSO4.Filtration and concentration of the hexane under reduced pressure (˜24torr) in a hot water bath (˜75° C.) gave 6.9 gm of slightly faint yellowoil (88.5% of the expected saturated conjunct polymers). The totalconjunct polymers removed by hydrogenation over Ni—Al at 100° C. and 500psi H₂ pressure was 94%.

Example 16

Example 15 above was repeated with 50 gm of spent ionic liquidcontaining 24.3 wt % (12.15 gm) conjunct polymers in 70 cc hexane in thepresence of 3 gm of Ni—Al alloy at 100° C. and starting hydrogenpressure of 500 psi. The reaction ran for 1.5 hrs. A total of 11.5 gm(94.6%) conjunct polymers were removed from the spent catalyst based onobtained saturated polymers and recovered CPs from the hydrolysis of 10gm portion of the treated ionic liquid catalyst. The remainder of thetreated ionic liquid catalyst was saved and tested for activity asdescribed in example 12.

Example 17 Hydrogenation of Conjunct Polymers in Spent ChloroaluminateIonic liquid Catalyst over Nickel Metal

As in Example 15 above, 25 gm of spent chloroaluminate ionic liquidcatalyst containing 15.5 wt % (3.87 gm) conjunct polymers in 60 mlanhydrous hexane (in 300 cc autoclave) was hydrogenated at 100° C. and500 psi hydrogen pressure over Nickel metal (3 gm) for 1.5 hours. Oncethe heating started, the pressure steadily started rising until itreached 946 psi at 100° C. The pressure dropped slightly to 910 psi atthe end of the run. The reaction was stopped and the organic phasecontaining the hydrogenated polymers was decanted off. The ionicliquid-Ni residue was rinsed with 2×50 ml anhydrous hexane. All theorganic layers were combined and dried over MgSO4. Filtration andconcentration to remove hexane gave 1.58 gm (41%) of the hydrogenatedpolymers as colorless oil. The ionic liquid catalyst was separated fromNickel metal by filtration. The ionic liquid catalyst was entirelyhydrolyzed giving 1.62 gm conjunct polymers (the total amount of CPsremaining in the catalyst). This indicates that hydrogenation overNickel metal led to the overall removal of 2.2 gm (58%) of the conjunctpolymers from the spent catalyst.

Example 18 Determination of the Activity of the RegeneratedButylPyridinium Chloroaluminate Ionic Liquid Catalyst by Hydrogenationover Ni—Al Alloy

The regenerated butylpyridinium chloroaluminate ionic liquid catalystdescribed in Examples 15 and 16 was tested for activity by using it asthe catalyst in the alkylation of isopentane with ethylene and comparingit with freshly-made catalyst. The alkylation of isopentane withethylene was done according to the following procedure A 300 ccautoclave was charged with 20 gm of ionic liquid catalyst, 100 gmanhydrous isopentane, 10 gm ethylene and 0.3 gm anhydrous HCl. Thereaction was then stirred ˜1200 rpm and heated to 50° C. at autogenicpressures. The starting pressure was usually 280-320 psi. The reactionwas usually complete when the pressure dropped down to single digits. Inthe case of slow going reaction, the reaction was allowed to go on for 1hr. At the end of the reaction, the reactor was vented out and a gassample was checked by GC for ethylene concentration. The liquid reactionmixture was allowed to settle into 2 phases. The organic phase wasdecanted and analyzed for product distribution by GC analysis. Thefollowing Table 3 draws a comparison among the freshly made, the spentand the regenerated catalysts.

TABLE 3 Fresh Ionic Spent Ionic Ni—Al Regen. Liquid Catalyst LiquidCatalyst Ionic Liquid Cat. Reaction Time 6-9 min. 60 min. 4-7 min.Starting 300 psi 286 psi 350 psi Pressure Ending pressure 11 302 psi 7iC5 wt % 72 98 61 C7s wt %: 2,3-DM-Pentane 8.23 0.9 8.5 2,4-DM-Pentane10 0.6 11.3 Other C7s 0.77 0.1 1.2 2,3DM/2,4DM 0.82 1.5 0.75

Example 19 Removal of Conjunct Polymer from Deactivated IL A by Reactionwith Isobutane

Deactivated IL A (14.50 gm) containing ˜18 wt % conjunct polymer wascharged to a nitrogen-filled 100 mL autoclave. Ten milliliters of HClgas measured at ambient temperature and pressure were added to theautoclave. The autoclave was then filled with liquid isobutane (81.6 gm)at ambient temperature.

The autoclave was heated to 100 C with stirring for 5 hours, then cooledto ambient temperature. In a drybox, the ionic liquid was removed andextracted with hexane to remove saturated conjunct polymer.

To measure the removal of conjunct polymer, 7.56 grams of the recoveredionic liquid were hydrolyzed. The resulting aqueous mixture wasextracted with hexane. After evaporation of hexane, 0.60 grams remained,indicating that after reaction with isobutane and HCl, the ionic liquidcontained 7.9 wt % conjunct polymer. This means that the treatment withisobutane and HCl removed ˜57% of the conjunct polymer originallypresent in the used ionic liquid catalyst.

There are numerous variations on the present invention which arepossible in light of the teachings and supporting examples describedherein. It is therefore understood that within the scope of thefollowing claims, the invention may be practiced otherwise than asspecifically described or exemplified herein.

1. A process for regenerating a used acidic catalyst which has beendeactivated by complexation with conjunct polymers by freeing theconjunct polymers from complexation by an addition of a basic reagent toform new complexes so as to increase the activity of the catalyst;wherein the used acidic catalyst is selected from the group consistingof H₂SO₄, AlCl₃, and an acidic ionic liquid catalyst.
 2. The processaccording to claim 1 wherein the acidic ionic liquid catalyst has beenused to catalyze a Friedel-Craft reaction.
 3. The process according toclaim 2, wherein the Friedel-Craft reaction is alkylation.
 4. Theprocess according to claim 1 wherein the acidic ionic liquid catalystcomprises an imidazolium, pyridinium, phosphonium or tetralkylammoniumderivative or their mixtures.
 5. The process according to claim 1wherein the acidic ionic liquid catalyst is a chloroaluminate ionicliquid.
 6. The process according to claim 4, wherein the acidic ionicliquid catalyst is a chloroaluminate ionic liquid.
 7. The processaccording to claim 1, wherein the used catalyst is an acidic ionicliquid catalyst.
 8. The process according to claim 1, wherein the usedacidic catalyst is selected from the group consisting of H₂SO₄ andAlCl₃.
 9. The process of claim 1, wherein the acidic ionic liquidcatalyst is a fused salt.
 10. The process of claim 1, wherein the acidicionic liquid catalyst is prepared from an organic-based cation and ananion.
 11. The process of claim 10, wherein the organic-based cation isselected from the group of an ammonium, a phosphonium, and a sulphonium.12. The process of claim 11, wherein the ammonium is pyridinium orimidazolium.
 13. The process of claim 1, wherein the acidic ionic liquidcatalyst is derived from an ammonium halide and a Lewis acid.
 14. Theprocess of claim 13, wherein the Lewis acid is selected from the groupconsisting of AlCl₃, TiCl₄, SnCl₄, and FeCl₃.